We have purified beta-ketoadipate-succinyl CoA transferases from Acinobacter calcoaceticus and Pseudomonas putida; we intend to compare the structures of these enzymes with the structures of enzymes that mediate other reactions in the beta-ketoadipate pathway. Additional studies will focus on the enzymes that form lactones from cis,cis-muconate and carboxy-cis,cis-muconate, respectively.